Electronic switching and computing device



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Gttorneg L.. E. FLRY ET LL ELECTRONIC SWITCHING AND COMPUTING DEVICES Filed Sept. 23, 1942 2 Sheezs-Shee-t 2 Envenors EFM@ Tfm/ Qorneg Patented June 1, 194sl ELECTRONIC SWITCHING AND COMPUTING DEVICE Leslie E. Flory, Oaklyn. and George A. Morton,

Haddon Heights, N. J., signora to Radio Corporation of America, a corporation of Delaware y Application september 23,1942, serial No. 459,404

Claims. (Cl. Z50-27) 1 This invention relates generally to electronic computers and particularly to electronic apparatus for counting or timing voltage pulses.

The basic circuit utilized in adapting the in-- vention herein to the various circuits to be described is the well known. trigger circuit of the general type described in "Theory and Applicationvoi Vacuum Tubes, by Herbert J. Reich. In its simplest form, this trigger circuit includes two triodes in which the grid of the first triode is coupled to the anode of the second triode through a coupling resistor, and the grid of the second triode is coupled to the anode of the first triode through a lsimilar coupling resistor. The cathodes of both triodes are grounded. Grid and anode potentials are applied to the respective electrodes through separate resistors. if desired, a gaseous discharge tube may be connected across one of the anode resistors to indicate circuit operation.

In operation. if a negative voltage is applied to the grid of the rst triode, the anode current of.l the triode will be reduced and the anode potential will became more positive. Due to the connection through the coupling resistor, the grid potential of the second triode will become more positive, causing an increase in the anode current of the second triode, with a resultant decrease in the second triode anode potential. 'I'his decrease in anode potential will in turn cause the grid potential of the first triode to become more negative. This action will continue until the anode current of the ilrst triode is cut oil'. The first triode will remain cut oi'f, and the second triode will remain conducting, until a positive potential is applied to the grid of the iirst triode, or a negative potential is applied to the grid of the second triode. In either instance, the tube operating conditions will be reversed, and the first triode will become conducting and the anode current of the second triode will be cut off.

One of the features of the instant invention is the utilization of such trigger circuits in cascade arrangement, whereby a predetermined change in polarization of one triode of the trigger circuit will generate a pulse to trigger or activate, a corresponding triode in a succeeding trigger circuit. As many trigger circuits as desired may be connected in cascade. A convenient arrangement comprises ten trigger circuits connected in casf cade, with a connection from the tenth to the ilrst, and an additional connection to the iirst of a succeeding bank of cascaded trigger circuits.

Such an arrangement provides a convenient counter in the scale of ten. Such a counter circuit may 'also be readily adapted to a scale having any other radex, or base of the counting system.

Another feature of the `invention is the use of the trigger circuit for controlling the operationl of a constant frequency source such as an oscillator. The output of the oscillator is applied to a counter circuit of the type described. The number of oscillations occurring during the controlled interval are a measure of the length of the interval.

Among the objects of the invention are to provide a new and improved means for counting voltage pulses. Another object of the invention is toprovide an improved means for utilizing conventional trigger circuits in cascade arrangement for counting voltage pulses. Still another object is to provide an improved means for connecting conventional trigger circuits in cascade arrangement to provide a continuous counter. A further object is to provide improved means for clearing the counter after each operation thereof, for conditioning the circuit for counting succeeding applied pulses. Another object is to provide a new and improved means for controlling the interval of oscillation of a constant frequency source. Still another object is to provide a new and improved means for controlling the interval of operation of a constant frequency source in combination with electronic means for counting the oscillations during the controlled interval. A further object is to provide a new and improved means for preventing the triggering of the oscillator operating interval by other than predetermined starting and stopping voltage pulses.

The invention will be described by reference to the accompanying drawings of which Figure l. is a schematic circuit diagram of a trigger circuit representative of the prior art; Figure 2 is a schematic circuit diagram of a counter circuit comprising one embodiment of the invention; Figure 3 is a schematic circuit diagram of a second embodiment of the invention: Figure 4 is a schematic circuit diagram of a third embodiment of the invention; and Figure 5 is Ia block diagram of a preferred combination of the circuits described in Figures 2,' 3 and 4. Similar referencenumerals are applied to similar elements throughout the drawings.

e Referring to the drawings, Fig'. 1 comprises a trigger circuit of the type described heretofore. The grid gi of a iirst triode I is connected to the anode p2 of a second triode 2 through a coupling resistor rl. The anode pi of the rst triode i is connected to the grid g2 of the second triode 2 throughA a secondv coupling resistor r2. The

anode coupling resistor r. A gaseous indicator tube 3, which may be a conventional'neon tube. is connected across the first anode resistor f to indicate when the anode potential exceeds a predetermined value characteristic of the anode current cut-off condition oi' the first tube In Fig. 2 a plurality of trigger circuits,`which may be ofrthe general type described in Fig, 1,

are connected in cascade arrangement by connecting the anode pl of the rst tube oi' the iirst trigger circuit A to the grid gl of the first tube of the second trigger circuit B through a first couplingv capacitor 4'. Similarly the anode pI of the first tube of the second trigger circuit B is connected to the grid of the first tube of a third trigger circuit C through a similar coupling capacitor l". Likewise the anode 11| of the first tube of the third trigger circuit C is connected to the grid ,0| of the first tube of a fourthtrigger circuit D through a similar coupling capacitor Ill connected in this cascade arrangement. As explained heretofore, the counter may be made continuous, by connecting the last trigger circuit ofV any bank to the input of the first trigger circuit. Pulses to be counted are applied to the ilrst grid gl of the rst tube I of each oi' the trigger circuits through separate second coupling capacitors 5. The second capacitors 5 should preferably be of lower capacity than the first coupling capacitors l, in order that control potentials due to the cascading of the trigger circuits may over-ride pulses applied through the capacitors 5. In order to compensate for the additional loading of the anode circuit of the rst trigger tube in each trigger circuit due to Vthe coupling to the next succeeding trigger circuit, capacitors 6 areconnected in parallel with each of the coupling resistors which connect the anode oi' each first tube to the grid of each second tube. If desiredcompensation may be provided by applying different bias voltages to the grids of the rst and second tubes of each trigger circuit.

In operation, if it is` assumed that trigger circuits A, C and D are polarized so that the anode currents vof the iirst tubes I of each of the trigger circuits are cut loil, and the second tubes 2 are conducting, while in trigger circuit B the lrst tube I is conducting and the anode current of the second tube 2 is cut oil, the neon tufbe 3b will be illuminated, indicating the different condition ofthe trigger circuit B. I-f `a negative pulse is applied to the pulse input terminals 8.

' which arefconnected to the capacitors 5 and ground, it will not affect the trigger circuits A, C, and D since the rst tube of each of these circuits is already cut off. However, the negative pulse will cut oil the anode currentof the iirst As many trigger circuits as desired may be 4 1 circuit C. Y Subsequent negative pulses applied to theterminals 6 will sequentially trigger succeeding trigger circuits in the same manner. 'I'he particular illuminated indicator lamp will indicate the total pulses applied. To clear the counter after each operation, a switch 1 is opened. This removes the negative bias from Y the second tubes of trigger circuits B, C and D, Y

and the first tube oi trigger circuit A, thereby tripping all trigger circuits except A into the same polarization, and causing the indicator tube 3a to be illuminated.

Fig. 3 isa counter circuit energized by pulses generated by a light responsive device IU, or other device to be timed, which produces a voltage of approximately square wave form. This l., voltage is amplified and phase inverted in a rst amplifier tube II, and applied to a diierentiating circuit comprising a capacitor I2 and a resistor 50. The square wave voltages are illustrated --by the graphs I4 and I5, while the voltage output of the differentiating circuit is 'illustrated by the graph I6. The differentiated voltage I6, is applied to a'second amplifier tube Il, the output ofwhich is phase inverted, as indicated by the graph I8. The thus ampliiied voltages are next applied .to the input of a clipping amplier or rectifier I9 which passes only the negative half-cycle of each voltage pulse, as indicated by the graph 22. This pulse corresponds to the start of pulse I4. The pulses I8 are also applied to a phase inverter tube 20 and rectified by a second rectifier tube 2| which passes similar negative half-cycles of the pulses I8, as indicated by the graph 23, which correspond to the end of pulse I4.

The negative pulses 22, derived from the rst rectifier tube I9, are applied to key the grid gl of a rst tube 3| of a trigger circuit which includes the tube 3| and a second tube 32. The negative half cycles derived from the second rectifier tube 2| are applied to the grid g2 of the second trigger tube 32. The plate resistors f5 and r6 and the grid resistors r3 and r4 are connected as shown in the previously described Fig. 1. The cathodes of the tubes 3| and 32 are connected to ground through the cathode resistors 33 and 34 respectively. A coupling circuit, comprising the parallel connected resistor 35 and capacitor 36, is connected between the grid y| of the first trigger tube 3| and the anode p2 of the second trigger tube 32. A secondh coupling circuit, comprising the parallel connected resistor 31 and capacitor 38, is connected between the anode pI of the first trigger tube ative potential to the grid al of the nrst trigger.

tube 3|, to cut of! its anode current. When the first trigger tube 3| is cut olf, the potential across the cathode resistor 33, which is connected to the terminals 39, is reduced. A control potential is derived from the terminals 39, and is utilized to control the interval of oscillation of aconstant frequency source, `to be described hereinafter. When the light sensitive device I0 is de-energized, the negati-ve pulse 23 is applied to cut off the anode current of the trigger tube 32, thereby reversing the polarization of the trigger tubes. Since the negative bias potential derived from the anode of the tube 32 is removed, the trigger tube 3| is restored to a conducting condition and the voltage across the cathode resistor 33 applied to the terminals 33 is increased.

Fig. 4 is similar to Fig. 3 with the exception that separate starting and stopping pulses are provided, and additional trigger circuits or multivibrators are included for deconditioning, or locking, the oscillator control trigger circuit after each change in its polarization. In addition, selective means are provided for reconditioning the circuit for succeedng starting and stopping pulses. The circuit includes an amplifier il. a differentiating circuit comprising the capacitor I3 and the resistor 53, and a rectin'er I9, for deriving a neative pulse 22 as described in connection with Fig. 3. An additional amplifier tube.

a diiierentiating circuit comprising a capacitor I2' and a resistor 5l'; and an additional rectifier' tube I3' is also provided forderiving a second group of negative pulses of similar type. A trigger circuit, which is similar to the trigger circuit described in Fig. 3, is connectedso that the negative pulses!! derived in the first rectiiier I9 are applied to the grid VI of the iirst tube 3|. while negative pulses derived from the second rectifier I9' are applied to the grid g2 of the second trigger tube 32.

A starting pulse, applied to the terminal 4|. causes the first trigger tube 3| to be cut ofi. A stopping pulse. applied to the terminal 42. causes the second tube 32 to be cut 0K and the iirst trigger tube 3| to conduct. In order to prevent succeeding pulses applied to the terminals 4i and 42 affecting the operation of the trigger circuit 40, a second trigger circuit, or multivibrator, 43 is connected to the output of the first rectifier I9 and a third trigger circuit, or multivibrator, 44 is connected to the output of the second rectifier I9'. When a pulse is applied to the terminal 4i, the trigger circuit 43 generates a positive potential across the cathode resistor 45. This positive potential is applied to the cathode of the amplifier tube i I to bias of! the tube anode current, thereby preventing any succeeding pulses. from affecting the operation of the circuit. The operation of the third trigger circuit 44 produces controlling potentials similar to those described for the second trigger circuit 43: the controlling potentials from the third trigger circuit are applied to the cathode of the amplifier I I'. A "start pulse applied to the terminal 4I will provide a control potential across the terminals 3! which will be unaffected by any other applied pulses, until such time as the stop pulse is applied to the terminal 42. Pre-set pulses may be derivedin any suitablemanner and applied to the terminals 45' and .48. respectively, of the second and third trigger circuits 43. 44, to recondition the circuits for oneration by succeeding "start" or "stop" pulses. The .third trigger circuit 44 is normally in the state of polarization which prevents transmission of stop pulse. An activating pulse either from the start circuit. or a delay circuit. not shown. reverses the polarization oi' the trigger circuit 44. so that a p" pulse on 42 will reverse the polarization of the control trigger circuit 4l.

Pig. 5 is a block diagram of a typical arrangement for utilizing the circuits described in Figs. 2. 3 and 4. A control circuit Il, which. for example. may be of either of the types described in .'Figav and 4, provides a control potential at its terminal 3l in response to pulses applied to the input terminals 4l. This potential is applied to a. constant frequency source Il, such as a crystal controlled oscillator, to control the interval 'of oscillation thereof, for example, by blocking and unblocking the circuit. The output of the oscillator ll is applied to the input of an electronic counter circuit 52. which may be of the type described in Fig. 2. The indicators of the counter circuit may also be of theitype described in Fig. 2 wherein'neon discharge tubes indicate the number of pulses applied to the input of the counter circuit. The duration of the control voltage derived from the terminals 33 of the timing circuit `50 will determine the interval of oscillation of the oscillator 5I. Since the oscillator output is of constant frequency, the oscillations counted by the counter circuit 5.2 will be a direct indication of the time interval provided by the timing circuit 50.

Thus the invention described comprises an electronic counter circuit utilizing trigger circuits or multivibrators in cascade arrangement, and means for utilizing additional trigger circuits for generating control potentials for controlling the oscillation interval of a constant frequency source. The oscillation interval is measured by counting pulses derived from the constant frequency source which are applied to the input of the electronic counting circuit.

We claim as our invention: A

1. A timing circuit including a source of timing pulses. means for shaping said pulses, a trigger circuit including at least two thermionic tubes each including at least an anode, a cathode, and a control electrode. means interconnecting the anodes of each of said tubes to thecont'rol electrode of another of said tubes, means for applying said shaped pulses to one of said interconnected tube circuits of said trigger circuit and to vary the relative polarization of said tubes, means for deriving control potentials from said trigger circuit characteristic of the polarization of said tubes of said trigger circuit, a source of oscillations, an oscillation counter. means responsive to said control potentials for Y controlling the duration of said oscillations'a second trigger cir cuit. means for applying said pulses to said second trigger circuit to trigger said second .trigger circuit. means for deriving a control voltage from s'aidsecond trigger circuit, and means for applying said voltage to said timing pulse source to bias-ofi' succeeding applied pu 2. Apparatus of the type described in claim l including means connected to said second trigger circuit for suppressing said control voltage.

3. 'I'he combination of a source of oscillations,l

an oscillation counter, means for'applying a timing pulse of a substantially square. wave shape, timing pulse shaping means for producing a control pulsein response to the beginning of said .timing pulse. a trigger circuit of the type wherein a pair of triodes each have operating potential applied through separate anode and cathode resistors and each triode has its grid coupled to the anode of the other-triode through a capacitor shunted by a resistor. and means responsive to said control pulse for applying said control pulse to one ofsaid grids so that current conduction is shifted from one to another of said triodes and there is applied from one of said cathode resistors to said source of oscillations a potential whereby the supply of said oscillations to said counter is initiated.

4. The combination oi'l a source of oscillations,

an oscillation counter,'means forv applying timing pulses of a substantially square wave shape, timing pulse shaping means for producing separate control pulses at the beginning and at the end of said timing pulse, a trigger circuit oi.' the type wherein a pair of triodes each have operating potential applied through separate cathode resistors and each triode has its grid coupled to the anode of the other triode through a capacitor shunted by a resistor, ineans for applying one of said control pulses to one of said grids, means for reversing the polarity of the other of said control pulses and applying said reversed control pulse to the other of said grids, and means responsive to the voltage ofone of said cathode resistors for starting and stopping the supply of said oscillations to said counter.

5. A timing circuit including a source of timing pulses, means responsive to said timing pulses v for producing control pulses of the same polarity at the beginning and at the end of said timing pulses, a trigger circuit including at least two thermionic tubes each including at least an anode, a cathode and a control electrode, means interconnecting the anode of each of said tubes to the control electrode of the other of -said tubes, means for applying a rst one of said control pulses to one of said interconnected ,tube circuits of said trigger circuit and the next succeeding one of said control pulses to the other of said interconnected tube circuits of said trigger circuit to vary the relative polarization of said tubes of said trigger'circuit, means for deriving control potentials from said trigger circuit characteristic of the polarization of said tubes of said trigger lSil Aug. 1939, pp. 14-17.

circuit, a source of oscillations, an oscillation counter connected to the output of said source,

and means responsive to one of said control po- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,932,589 Holden Oct. 31, 1933 2,113,214 Luck -.--Apr. 5, 1938 2,132,654 Smith Oct. 11, 1938 2,158,285 Koch May 16, 1939 2,272,070 Reeves Feb. 3, 1942 2,293,177 Skellett Aug. 18, 1942 2,306,386 Hollywood Dec. 29, 1942 2,310,105' Mitchel Feb. 2, 1943 2,324,314 Michel July 13, 1943 2,332,300 Cook Oct. 19, 1943 FOREIGN PATENTS Number Country Date 355,705 Great Britain Aug. 24, 1931 356,111 Great Britain Aug. 24, 193i OTHER REFERENCES Electronics, Trigger Circuits," by H. J. Reich, 

